76-cm Rows Research Articles

Hessian Fly Control with Granular Insecticides Applied at Planting, 1985

Abstract The efficacy of selected seed treatment and granular formulations of insecticides was evaluated for Hessian fly control. Winter wheat was planted on 21 Oct at the Bledsoe Research Farm in Pike County, Ga. Plots measuring 25 × 7 ft were established in a randomized complete block design with 4 replications. Seed was drill planted with a Tye drill in 8-inch rows at 90 lb of seed/acre. Granular insecticides were broadcast immediately after planting with a Gandy bicycle applicator equipped with two 10-inch banders. Granules were incorporated in to the upper 0.5 inches of soil by raking each plot. All plots were sampled 45 days after planting by digging al! plants in 2 random samples of 30 cm of row. The number of tillers and percentage of infested tillers were determined. Data were analyzed with a 2-way analysis of variance and Duncan’s multiple range test.

Velvetbean Caterpillar Control in Soybean, 1987

Abstract The experiment was located in Gadsden County, Fla., and planted 12 Jun. Plot size was 6 rows × 15 m with a 76-cm row spacing. Experimental design was a randomized complete block, with 4 replications. All treatments were applied 4 Sep, except for a treatment of the velvetbean caterpillar (VBC) plaque-purified nuclear polyhedrosis virus (AgNPV), which was applied 28 Aug. All treatments were made with a 2-row, CO2-powered backpack sprayer equipped with three D3 nozzles/row. The chemicals were applied at 36 psi, with a spray volume of 25 gal/acre. Efficacy data were made by taking 25 sweeps/plot with a 38-cm-diam sweep net on each of 5 dates.. The 2 center rows of each plot were not sampled, and yield estimates were made by harvesting 12 m of these rows on 2 Oct.

Velvetbean Caterpillar Control in Soybean, 1986

Abstract The experiment was located in Gadsden County, Fla., and planted on 4 Jun. Plot size was 8 rows × 15 m with a 76-cm row spacing. Experimental design was a randomized complete block, with 4 replications. Treatments were applied on 3 Sep. All treatments were made with 2-row, CO2-powered backpack sprayer. The sprayer was equipped with three D3 nozzles/row. The chemicals were applied at 36 psi, with a spray volume 25 gal/acre. Efficacy data were taken by taking 25 sweeps with a 38-cm-diam sweep net on 2, 7, 14, and 28 days after treatment. A different row was sampled in each plot on each sample date.

RESPONSE OF TRITICALE TO THE HESSIAN FLY (DIPTERA: CECIDOMYIIDAE)

Hessian fly infestation on triticale (X triticosecale Wittmack) has not been previously reported. Severe infestations on wheat in Georgia prompted the evaluation of triticale germplasm in the greenhouse to known biotypes of Hessian fly and in the field to natural populations. Susceptible triticale plants showed the same characteristics as susceptible wheat plants. ‘Beagle 82’, ‘Wytch’, and ‘Marta’, as well as several experimental lines, were highly resistant to biotype D Hessian fly. ‘M2A-Beagle’ and ‘Great Northern’ were the only entries highly resistant to biotype E, the predominant biotype population in the Southeast. The total number of flies per 30-cm row averaged 58 and 283 at Experiment and Plains, respectively. Morrison had the lowest percentage of infested tillers. ‘Jenkins’ and ‘Council’ were the most severely infested cultivars. Crosses have been made to determine the genetics of Hessian fly resistance identified in these studies.

Shade Development Effects on Pitted Morningglory (Ipomoea lacunosa) Interference with Soybeans (Glycine max)

‘Ransom’, ‘Govan’, and ‘Bragg’ soybeans [Glycine max(L.) Merr.] were seeded in 30-, 61-, and 91-cm row spacings to achieve a uniform population of 323 000 plants/ha. In 1979 and 1980, shade development within the row was similar for all row spacings, but 15 cm from the row the inflection point occurred earlier when soybeans were seeded at the 30-cm row spacing. In 1979, shading 30 cm from the row was similar with the 61- and 91-cm row spacings, but in 1980 the 61-cm row spacing provided earlier shading. Shading within the row and 15 and 30 cm from the row was similar for all cultivars in 1979, but Govan and Bragg shaded row middles earlier than Ransom at the 91-cm row spacing. In 1980, shade development in the row was similar for all cultivars, but delayed shading was observed between the rows with Ransom. In 1979, maximum soybean seed yields were produced with 2, 2, and 0 weed-free weeks at the 30-, 61-, and 91-cm row spacings, respectively. In 1980, 2 weed-free weeks prevented soybean seed yield reductions at all row spacings. In 1979, Ransom, Bragg, and Govan required 4, 2, and 0 weed-free weeks, respectively, for maximum seed yields. In 1980, all cultivars achieved maximum seed yields with 2 weed-free weeks.

Evaluation of a 76-cm Row for Cotton Production

ABSTRACT FIELD studies were conducted on three soil types to evaluate the production potential of 76-cm rows in the Mississippi Delta. Cotton was efficiently grown and spindle-harvested in both 76-cm and 102-cm rows. Cotton yield was influenced by year, irrigation, variety, and row spacing. In 1982, the combination of irrigation and 76-cm rows on Bosket soil resulted in higher lint yield than from irrigated 102-cm rows, but the opposite was true in 1983 and 1984. Of the eight varieties evaluatd on the Beulah soil in 1982, five varieties (DPL-30, DPL-61, DPL-90, MCN-235 and STV-506) produced more lint on 76-cm rows than on 102-cm rows, when the plots were irrigated. Without irrigation, all varities produced more on 102-cm rows. Fiber properties were not influenced by row spacing, but percent lint gin turnout was found to be significantly higher on 76-cm rows than on 102-cm rows with an average difference of one percent. Yields from a one-year study on Tunica clay were significantly lower on 76-cm rows than on 102-cm rows. The 76-cm rows were more difficult to defoliate with aircraft than the 102-cm row.

Effect of Shoot Density and Crop Control on Growth, Yield, Fruit Composition, and Wine Quality of ‘Seyval blanc’ Grapes

Abstract A factorialized thinning level/shoot density experiment which was started in 1980 demonstrated that ‘Seyval blanc’ grapes benefits from cluster thinning in terms of vine size maintenance, cane ripening, berry weight, and Brix. Reducing shoot density led to increased cane ripening. Concomitant increases in cluster exposure improved fruit composition and led to higher berry weights. However, maintaining reasonably high shoot densities (4 shoots/30 cm of row or more) also was essential to maintain yield and vine size, even when crop was controlled by thinning. Levels of 4 shoots/30 cm of row and 17 clusters/500 g cane prunings are recommended to maximize yield and maintain reasonable fruit quality and vine size. Postbloom cluster thinning was found to reduce the incidence of bunch rot and to reduce the production of 2nd crop in 1982, without affecting any parameters of yield or fruit composition.

Evaluation of Insecticides For Control of Trheecornered Alfalfa Hopper on Soybean, 1984

Abstract Plots of Bragg soybean were established near Hamburg, LA. Plots measuring 15.2 m by 8 rows (76-cm row spacing) were arranged in a randomized complete block design with 4 replications. All plots were treated at the R4 growth stage on 18 Aug. Insecticides were applied with a CO2 pressurized backpack sprayer calibrated to 15.4 gal/acre at 30 psi with 8002 nozzles. Posttreatment samples were taken in each plot at 3, 7 and 14 days using 50 sweeps per plot for adults and 1 beat-board sample per plot (1.0 m of row) for the nymphs.

Influence of Population Density of Immatures on Size, Longevity, and Fecundity of Adult Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

Field tests with controlled infestations of eggs of Diabrotica virgifera virgifera LeConte showed that larvae at higher infestation rates were stressed for food. The percentage of insects reaching the adult stage was significantly reduced at infestation rates above 600 eggs per 30.5 cm of row. Adults were significantly smaller at infestation rates above 300 eggs, they were shorter-lived at rates above 600 eggs, and they were less fecund at infestation rates above 1,200 eggs per 30.5 cm of row. These results indicate that high densities of immatures have a deleterious effect on number, size, longevity, and fecundity of adult western corn rootworms.

Weed Management in Minimum-Tillage Peanuts (Arachis hypogaea) as Influenced by Cultivar, Row Spacing, and Herbicides

Field experiments were conducted in 1982 and 1983 on a Dothan sandy loam (Plinthic Paleudult) at Headland, AL, to investigate minimum-tillage production of peanuts (Arachis hypogaeaL.). The experiments included two peanut varieties: a) ‘Pronto’ (an earlier maturing Spanish type), and b) ‘Florunner’ (a later maturing runner type). Two row-spacing patterns were used: a) conventional 91-cm rows, and b) a modified twin 18-cm row pattern. A constant seeding rate (140 kg/ha) was used regardless of row spacing. Six herbicide systems were evaluated within each combination of variety and row spacing. The Florunner variety outyielded the Pronto variety across both years and weed management systems. Modified twin 18-cm rows outyielded conventional 91-cm rows across years and peanut varieties. Two of the six weed management systems were successful: 1) paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) + oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) (preemergence), paraquat (ground cracking), naptalam (N-1-naphthylphthalamic acid) + dinoseb (2-sec-butyl-4,6-dinitrophenol) (postemergence); and 2) paraquat + pendimethalin [N-(1-ethylpropyl-3,4-dimethyl-2,6-dinitrobenzenamine] (preemergence), acetochlor [2-chloro-N(ethoxymethyl)-6’-ethyl-o-acetotoluidide] + dinoseb (ground cracking), and cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazine-2-yl]amino]-2-methylpropionitrile} (early postdirected spray). Both systems provided the best overall control of Texas panicum (Panicum texanumBuckl. ♯ PANTE), Florida beggarweed [Desmodium tortuosum(Sw.) DC. ♯ DEDTO], and sicklepod (Cassia obtusifoliaL. ♯ CASOB) and were acceptable for use in minimum-tillage peanut production.

Greenbug (Biotype E) Control on Grain Sorghum with Foliar Applied Insecticides, 1983

Abstract This field test was conducted in a dryland field of grain sorghum at the Kans. Br. Agric. Exp. Stn., Garden City, KA. Eleven insecticide treatments and an untreated check were replicated 4 times in a randomized complete block design. Plots were 4 rows wide (76-cm row spacing) and 10.7 m long. Treatments were applied as broadcast sprays over the row with a compressed air backpack sprayer delivering ca. 145 liters/ha at an operating pressure of 1.4 kg/cm2. A single application of insecticide was made on 2 Aug at which time plants were in the boot stage. Air temp at application was 24.4°C and wind was recorded at 8 km/h from the SW. Rainfall during the posttreatment sampling period was 0.25 cm on 4 Aug. Greenbugs were visually counted on 4 plants in each plot on 29 Jul (pretreatment) and 5, 9, 16 Aug (posttreatment). Yields were determined by machine harvesting the 2 center rows of each plot on 20 Sep and converting the data to kg/ha at 12.5% moisture.

Row Pattern and Weed Management Effects on Peanut Production1

Abstract Field experiments were conducted from 1981 through 1983 on a Dothan sandy loam (Plinthic Paleudults) at Headland, Alabama, to investigate the effects of row patterns and weed management systems on weed control, peanut yield, and net returns to land and management. Treatments consisted of three row patterns, a) conventional 91-cm rows, b) dual twin 18-cm rows, and c) triple twin 18-cm rows, and six weed management systems ranging from none to various combinations of herbicide and mechanical inputs. The experimental area was naturally infested with bristly starbur (Acanthospermum hispidum DC), sicklepod (Cassia obtusifolia L.), Florida beggarweed [Desmodium tortuosum (Sw.) DC.], large crabgrass [Digitaria sanguinalis (L.) Scop.], and Texas panicum (Panicum texanum Buckl.). Results showed that weed control was affected somewhat by row patterns with broadleaf weeds being more responsive to row pattern manipulation than grass weeds. Weed fresh weights were generally lower as row patterns narrowed from conventional 91-cm spacing, however exceptions did occur. Highest yields and net returns were obtained when peanuts were planted in the dual twin 18-cm rows and weed management included benefin applied preplant incorporated, plus alachlor applied preemergence, and two timely cultivations.

Effects of Insecticide, Weed-Free Period, and Row Spacing on Soybean (Glycine max) and Sicklepod (Cassia obtusifolia) Growth

Results from identical experiments conducted at Headland, AL, and Plains, GA, from 1980 through 1982 show insecticide treatment had little effect on soybean [Glycine max(L.) Merr. ‘Coker 237′] growth and morphology. Maximum insecticide applications increased soybean seed weight in two of five trials. Soybeans maintained free of sicklepod (Cassia obtusifoliaL. ♯3CASOB) for 4 weeks after emergence produced yields equal to those receiving season-long control in all trials, and 2-week control was equal to season-long maintenance in three trials. Length of weed interference-free maintenance did not affect soybean height. The number of pods per plant and seed weight were decreased when there was no control. Sicklepod shoot fresh weight and numbers decreased as the weed-free period increased from 0 weeks through the season. Row spacing had no effect on soybean height or seed size; however, the number of pods per plant was higher in 80- than in 40-cm rows. Row spacing influenced yield in only one trial where 20-cm rows outyielded 40-cm rows. A significant interaction occurred between the weed-free period and row spacing in two trials. Soybeans in 20-cm rows outyielded those in 40- and 80-cm rows when sicklepod was not controlled (i.e., 0 weeks interference-free maintenance).

Diploid‐Tetraploid Comparisons in Rye. I. Forage Production1

Autotetraploids differ from their diploid counterparts in many morphological, physiological, cytological, and ecological characteristics. The tetraploidy effect on the amount and environmental stability of rye (Secale cereale L.) forage production was examined in this study. Six populations consisting of three diploid (2x) cultivars (‘Florida Black’, ‘Gator’, ‘Explorer’) and their autotetraploid (4x) derivatives were grown in two late fall‐winter‐early spring forage seasons (1979–1980, 1980–1981) at Gainesville (29°40′ N Lat) and Quincy (30°35′ N Lat), Fla., at two seeding rates (0.5, and 1.0 viable seeds/linear cm of row). Forage weight was obtained at a total of 16 clipping dates among seasons and locations (Gainesville—four dates in both seasons, Quincy—three dates in 1979–1980 and five dates in 1980–1981). The direction and magnitude of the differences between the forage production of the 2x and corresponding 4x populations were not consistent and were influenced by genetic background (2x cultivar source) and clipping dates within season and location. Apparently, the tetraploid effect was altered by genetic factors and many interacting environmental forces. Significantly higher production from the higher seeding rate was obtained primarily at the earlier clipping dates within each season and location but seeding rate interactions with all genetic and environmental variables were not significant. No differences among populations in environmental stability were found.

Cultural Practices Affecting Season-Long Weed Control in Irrigated Corn (Zea mays)

Season-long weed control has been a goal of some producers of irrigated corn (Zea maysL.) to reduce competition, lessen weed seed production, facilitate crop harvest, improve water efficiency (particularly with furrow irrigation), and improve aesthetic properties of fields. Field experiments were conducted for 3 yr on sprinkler-irrigated corn on a loamy fine sand. Five herbicides applied at layby generally provided season-long control of grass weeds and reduced weed seed production up to 100%. Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] was particularly effective. Yields of irrigated corn were not increased by layby herbicide application. Use of corn rows spaced 91 cm apart and use of a shorter, early-maturing, horizontal-leaf corn cultivar resulted in greater weed growth and weed seed production than did use of 76-cm rows and a taller, full-season, upright-leaf corn cultivar. After nearly complete weed control with herbicides for 2 yr, withholding herbicide use in the third year allowed weed growth which reduced corn yield. Indications were that weed control efforts need to be continuous in irrigated corn production.

Field Competition between Ivyleaf Morningglory (Ipomea hederacea) and Soybeans (Glycine max)

Detrimental effects on growth and yield of soybeans [Glycine max(L.) Merr. ‘Amsoy 77′] from density and duration of competition by ivyleaf morningglory [Ipomea hederacea(L.) Jacq. ♯3IPOHE] was evaluated in 1981 and 1982 near West Lafayette, IN. Ivyleaf morningglory was planted at densities of 1 plant per 90, 60, 30, and 15 cm of row in 1981 and 1 plant per 60, 30, 15, and 7.5 cm of row in 1982. Each density of ivyleaf morningglory competed for 22 to 46 days after emergence and the full season in 1981, and for 29 to 60 days after emergence and the full season in 1982. The best indicators of competition effects were leaf area index, plant dry weight, and yield of soybeans. Ivyleaf morningglory was more competitive during the reproductive stage of soybean growth. Photosynthetic irradiance and soil moisture measurements indicated that ivyleaf morningglory does not effectively compete for light or soil moisture. All densities of ivyleaf morningglory could compete with soybeans for 46 and 60 days after emergence in 1981 and 1982, respectively, without reducing soybean yield. Full-season competition from densities of 1 ivyleaf morningglory plant per 15 cm of row significantly reduced soybean yield by 36% in 1981 and 13% in 1982. The magnitude of soybean growth and yield reduction caused by a given density of ivyleaf morningglory was greater when warm, early season temperatures favored rapid weed development.

Leaf area display and light interception in short-season soybeans

Abstract Several studies have shown that little movement of carbohydrate occurs in soybean ( Glycine max (L.) Merr.) from a leaf at one node to nodes more than two removed from the source node. Most light is intercepted in the upper periphery of the soybean canopy, but most of the seed yield occurs on the lower central nodes of the soybean plant. Thus, this study was designed to examine leaf area display and light interception patterns in the crop canopy in relation to yield production sites of two varieties of short-season indeterminate soybeans. Altona and Evans soybeans were planted in South Deerfield, MA on 19 May 1982 in rows 25 cm and 75 cm apart. Plots were overseeded by 50% into a fine sandy loam (Typic Udifluvents) and later thinned to populations of 25, 50 and 75 plants per m 2 . Light readings, taken weekly when weather permitted, were integrated over 1 m across and parallel to soybean rows, with the sensor placed on the ground, 25 and 50 cm above the ground and above the canopy dependent on plant height. Growth samples were taken biweekly with samples for leaf area determination divided into five strata, separated on the basis of point of attachment and display of the leaves. Soybean plants grown in narrow rows (25 cm) had a greater leaf area index, intercepted more light and yielded 23% more than soybeans grown in wide rows. For seed yield there was a variety-row width-density interaction, with Evans requiring a lower density for maximum yield than Altona in the 25-cm row width. Seed yield averaging 346.3 g m −2 for Evans was 32% greater than the average for Altona. Although most light interception, and therefore photosynthate production occurred in the upper regions of the plant canopy, many of the leaves displayed there were attached to nodes lower in the plant. Thus carbohydrates were suppled to lower regions of the plant, from these leaves, where most of the yield was found to occur. However leaves attached low in the canopy were still somewhat shaded by upper leaves, thus it is probable that greater efficiency of production could be obtained by concentrating breeding effects for improved canopy architecture with deeper light penetration into the canopy.

INFLUENCE DE LA FERTILISATION AZOTEE ET DE L’ECARTEMENT ENTRE LES RANGS DE CEREALES-ABRI RECOLTEES COMME FOURRAGE SUR L’ETABLISSEMENT DE LA LUZERNE

The effect of companion crop management on the establishment of alfalfa was evaluated. The studied variables included species of cereals, row spacing and seeding rate of companion crop, stage of maturity of the companion crop at harvest, and an additional nitrogen fertilizer application. The cereals were harvested as forage. In the year after the seeding year, the first yield of alfalfa was determined. In seven trials, forage yields of a pure stand of alfalfa were 3350 kg/ha in the first cut of the seeding year. These yields averaged 60% of forage yields obtained from the combination of alfalfa and companion crop. However, cereals substantially reduced the total digestible nutrients, crude protein and calcium contents of the forage as compared to the pure alfalfa. The additional 38 kg/ha of nitrogen at tillering provided an extra yield of 600 kg/ha. Row spacing had little or no effect on forage yield. Even though wider spacings has considerably reduced seeding rates increased spacing from 18 to 54 cm did not affect barley yield while wheat was reduced by 400 kg/ha and oat increased by 300 kg/ha. Also, the average number of stems per meter of row increased by 89% with an average weight gain of 23% for each stem at the 54-cm spacing. At the first cut in the year following establishment, yields of alfalfa established with a companion crop were equal to or lower than those in pure stand. Yield reductions varied from 0 to 13% with barley and wheat but approached 30% when oats were seeded in 18-cm rows. However, the yield reduction was only 14% in the 54-cm row spacing of oats.Key words: Medicago sativa L., nitrogen fertilization, companion crop

Weed Management in Cotton (Gossypium hirsutum) Grown in Two Row Spacings

Tillage plus trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and prometryn [2,4-bis (isopropylamino)-6-(methylthio)-s-triazine] and tillage plus trifluralin and fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] applied as soil-incorporated preplanting treatments were compared with tillage alone in cotton (Gossypium hirsutumL.) grown in 51-cm and 102-cm rows on fine sandy loam soil. Over 3 yr, cotton grown in 51-cm rows yielded 15% more than cotton grown in 102-cm rows. Final cotton emergence was not altered by weed-control treatment or by planting pattern. Weed-control treatments with herbicides provided essentially complete, season-long control of grass and broadleaf weeds. At cotton layby, more weeds were in no-herbicide plots with 51-cm rows compared with 102-cm rows, but at cotton harvest numbers of weeds in both row patterns were essentially equal.

Nodulation, N2 Fixation, and Seed Yield of Navy Beans as Influenced by Inoculant Rate and Inoculant Carrier1

AbstractPeat is the most commonly used carrier of Rhizobium sp. (rhizobia) in inoculants. The lack of suitable local peat in many areas of the world leads to interest in other materials as carriers of rhizobia. The purposes of these studies were 1) to compare potential carriers of Rhizobium phaseoli for their ability, under field conditions, to supply viable rhizobia to promote nodulation, N2 fixation, and increased seed yield of navy beans (Phaseolus vulgaris L.), and 2) to determine the optimum rate of inoculation with Rhizobium phaseoli to promote nodulation, N2 fixation, and increased seed yield of navy beans in two soils in Minnesota, a loamy sand (sandy, mixed, Udorthentic Haploborall) and a silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludoll).In 1978, five inoculation rates (ranging from 1 to 108 cells/ cm of row) of liquid suspensions of R. phaseoli inoculants were applied at planting. In 1979, R. phaseoli in six inoculant carriers, peat, charcoal, vermiculite, corn (Zea mays L.) cobs, peanut (Arachis hypogaea L.) hulls, and liquid medium, was used to inoculate navy beans at rates of 2.5 ✕ 104 and 5 ✕ 106 cells/cm of row. Nodule numbers and weight, acetylene reduction rates, seed yield, and seed N percentage were determined.In 1978, in most parameters measured, inoculation rates of 105—106 cells/ cm were required for a statistically significant increase over the lowest inoculation rate. In 1979 there was no effect of inoculation on a soil with a relatively high population of soil R. phaseoli (104 cells/g soil) and relatively high mineral N content (30 ppm). On a soil with an indigenous population of <10 cells/g soil and mineral N content of 8 ppm, peat and charcoal inoculants resulted in the highest seed yield, nodule numbers and weight, and acetylene reduction rates. Peanut hulls and corn cobs gave the poorest responses. These results indicate that peat, charcoal, and vermiculite can be successfully used as carriers of R. phaseoli but peanut hulls and corn cobs are unsatisfactory.